if you’re already familiar with the unwrapping process, then you don’t have much problem. Once you’re satisfied with the layout do this (in version 2.5+):
The Export:
[ul]
[li]click “UV” on the UV-viewport menu[/li][li]select “Export UV Layout”[/li][li]Give the file a name, set your resolution and select a suitable format (e.g. jpg, png etc.)[/li][li]Save it![/li][/ul]
External Work:
[ul]
[li]Open the exported image in any Image editor of choice[/li][li]Do your texturing on the image and save the textures[/li][/ul]
The Return of the “Jedi”-Texture
First, Open blender and create a material. How?
[ul]
[li]Select the target mesh (the one that was unwrapped)[/li][li]On the Properties Pane, select the material tab[/li][li]Create a material (press new), and rename it appropriately[/li][li]Click the next tab (checker icon … texture tab) and create a new texture[/li][li]Rename the texture for convenience[/li][li]Under the texture name is a "type" parameter. Change that to “Image or Movie”[/li][li]Under mapping, change the Coordinates to UV[/li][li]Under Image, click “open” and locate the painted texture file[/li][li]open your textured image and you should be okay.[/li][/ul]
I think you can figure the rest out.
At this point, you should be looking at a texture mapped mesh on your 3D-viewport. If not, switch the 3D-view type to “textured” and make sure GLSL shading is enabled.